Chapter 24: Glycogen Dehydration

Question 1

Glycogen is highly ______ homopolymer for only ______ present in all tissues

Answer 1

branched
glucose

Question 2

Largest stores of glycogen are in

Answer 2

liver and muscle

Question 3

Function for glycogen in the liver

Answer 3

Glycogen synthesis and degradation maintain glucose levels for the needs of the whole body
Maintains blood glucose concentration

Question 4

Function for glycogen in the muscle

Answer 4

(Selfish)
Stores glycogen to provide energy just for muscle contraction

Question 5

Glycogen

Answer 5

Storage form of gluocse in animals (including humans)

Question 6

Glycogen releases glucose when

Answer 6

low energy (energy demands are high)
breakdown of glycogen to start cellular respiration with free glucose

Question 7

When does glucose polymerize to form glycogen ?

Answer 7

When organism has no immediate need for energy derived from glucose breakdown –> synthesis of glycogen

Question 8

Structure of glycogen

Answer 8

highly branched
alpha 1,4 linkages and alpha 1,6 linkages

Question 9

Why is glycogen being highly branched important?

Answer 9

Makes it possible to store and deliver energy quickly and store for long periods

Question 10

What must be needed for energy demand for glycogen degradation?

Answer 10

break 2 bonds: alpha 1,4 linkages and alpha 1,6 linkages

Question 11

Key regulatory enzyme for glycogen degradation

Answer 11

Glycogen phosphorylase

Question 12

Glycogen phosphorylase

Answer 12

key regulatory enzyme of glycogen degradation
degrades glycogen from nonreducing ends of the glycogen molecule
glycogen catalyzes phosphorylysis to form glucose 6 phosphate
breaks down alpha 1,4 glycosidic compound

Question 13

What enzyme breaks down alpha 1,4 glycosidic bond from nonreducing sugars?

Answer 13

Glycogen phosphorylase

Question 14

Does glycogen phosphorylase use phosphorlysis or hydrolysis

Answer 14

Phosphorylysis

Question 15

Phosphoglucomutase

Answer 15

converts glucose 1 phosphate to glucose 6 phosphate

(use of glucose 1,6 biphosphate intermediate)

Question 16

Transferase

Answer 16

transfer branch of 3 glucose residues to end of another branch

Question 17

Debranching enzymes (alpha 1,6 glucosidase)

Answer 17

Cleaves alpha 1,6 glycosidic bond at branch point to release free glucose

Question 18

Where is the only location of gluocse 6 phosphatase?

Answer 18

Liver
(NOT IN THE MUSCLE!)

Question 19

Liver glycogen breaks down to

Answer 19

glucose 6 phosphate with hydrolysis

Question 20

Glucose 6 phosphatase

Answer 20

gluocse 6 phosphatase in liver generates free glucose to enter blood and be used in different tissues

Question 21

Muscle glycogen breaks down

Answer 21

glucose 6 phosphate btained from glycogen breakdown enters glycoltic pathway directly
Does not have to be hydrolyzed to glucose and exported to blood stream

Question 22

Does glucose 6 phosphatase located in the muscle?

Answer 22

No

Question 23

Why is it advantageous that breakdown of glycogen gives rise to glucose phosphate to glucose?

Answer 23

Save 1 ATP that is used from glucose to gluocse 6 phosphate
So when we start from glucose 6 phosphate, it is able to generate an additional ATP

Question 24

After you eat a meal, does degradation of glycogen or synthesis of glycogen occur?

Answer 24

Synthesis of glycogen

Question 25

Regulation of synthesis and degradation of glycogen

Answer 25

reciprocally regulated: 1 activated and 1 inhibited

Question 26

Step 1 of glycogen synthesis

Answer 26

Glucose 1 phosphate react with UTP to generate UDP glucose (UDPG)
releases 2 phosphate

Question 27

UTP glucose

Answer 27

monomer used to extend glycogen chain in synthesis

Question 28

When adding UDP to gluocse, it is added to

Answer 28

growing chain

Question 29

Step 2 of glycogen synthesis

Answer 29

Uses glycogen synthase
catalyze formation of alpha 1,4 glycosidic bond using UDP glucose on growing chain

Question 30

What is key regulatory enzyme of glycogen synthesis?

Answer 30

glycogen synthase

Question 31

Glycogen synthase

Answer 31

key regulatory enzyme of glycogen synthesis
catalyze formation of alpha 1,4 bond using UDPG on growing chain

Question 32

What is the primer of glycogen synthesis?

Answer 32

Glycogenin

Question 33

Step 3 of glycogen synthesis

Answer 33

Branching enzymes
Cleaves alpha 1,4 linkage and transfers 7 glucose residues to form alpha 1,6 linkage

Question 34

Glycogen is _____ storage of glucose

Answer 34

efficient

Question 35

How much ATP required to incoporate dierty glucose into glucogen

Answer 35

2 ATP

Question 36

Complete oxidation of gluocse derived from glycogen yields:

Answer 36

31 ATP

Question 37

Glycogen phosphorylase interconvertable forms:

Answer 37

1. active phosphorylated phosphorylase a
2. inactive unphosphorylated phosphorylase b form

Question 38

Default state of liver phosphorylase is:

Answer 38

active phosphorylated phosphorylase a form

Question 39

The 2 forms of phosphorylase a and b exist in equilibrium:

Answer 39

1. active relaxed R state
2. less active T state

Question 40

equilibrium for phosphorylase a favors

Answer 40

R state

Question 41

equilibrium for phosphorylase b favors

Answer 41

T state

Question 42

What is allosteric negative regulator for glycogen degradation in liver?

Answer 42

Glucose

Question 43

High glucose in liver will shift equilibrium to

Answer 43

T state (tenseand inactive) of phosphorylase a

Question 44

Low glucose in liver will shift equilibrium to

Answer 44

R state (relaxed and active) of phoshorylase a

Question 45

Default state of muscle phosphorylase is:

Answer 45

inactive phosphorylase b form

since glycogen breakdown just needs to be active for muscle contraction and when resting muscle, enzyme is in inactive b form

Question 46

What are allosteric effectors of glycogen degradation in muscle?

Answer 46

AMP, ATP, glucose phosphate

Question 47

have low energy with high level of AMP (indicate low energy charge) in muscle:

Answer 47

shift from T to R (active) state of phosphorylase b

Question 48

high energy charge (high ATP and glucose 6 phosphate in muscle:

Answer 48

shift from R to T state (less active) of phosphorylase b

Question 49

Key regulatory enzyme in glycogen synthesis?

Answer 49

Glycogen synthase

Question 50

2 forms of glycogen synthase:

Answer 50

1. active nonphosphorylated a form
2. inactive phosphorylated b form

Question 51

Low glucose (glucose 6 phosphate) of glycolysis synthesis shifts

Answer 51

R state to T state (inactive phosphorylated b form)

Question 51

What is the activator of glycogen synthase?

Answer 51

glucose 6 phosphate and stabilizes R state

Question 52

High glucose (glucose 6 phosphate) of glycolysis synthesis shifts

Answer 52

T state to R state (more active nonphosphorylated a form)

Question 53

What two hormones signal need for glycogen breakdown?

Answer 53

Epinephrine and glucagon

Question 54

Epinephrine and glucagon activate and inhibit what

Answer 54

activate glycogen phosphorylase
inhibit glycogen synthesis

signal need for glycogen breakdown

Question 55

Insulin results in decrease in _____ and stimulation of _____

Answer 55

glycogen degradation
glycogen synthesis

Question 56

Insulin hormon activates what enzyme

Answer 56

glycogen synthase

Question 57

Glycogen synathase and glycogen phosphorylase are controlled by ______ and _______

Answer 57

covalent modification
allosteric control

Question 58

Protein Phosphatase 1 (PP1) shifts glycogen metabolism from _____ to ________

Answer 58

degradation
synthesis

Question 59

Protein phosphatase 1 (PPI) reverses effects of

Answer 59

kinases

Question 60

Protein phosphatase 1 removes:

Answer 60

Removes phosphoryl groups from glycogen synthase b and convert it to active form –> stimulate glycogen synthesis
Removes phosphoryl groups from phosphorylase kinase and phosphorylase a –> inhibit glycogen degradation